Clinical manifestations and treatment outcomes for patients with Pseudomonas endocarditis

To investigate clinical outcomes of patients with Pseudomonas endocarditis and identify factors associated with treatment failure. Adult patients meeting definitive Duke's criteria for Pseudomonas endocarditis at 11 hospitals were identified between May 2000 and February 2024. Failure was defined as death or microbiological failure by day 42. First-line therapy consisted of cefepime, piperacillin/tazobactam, ceftazidime or ceftolozane/tazobactam alone or in combination. Forty-eight patients met inclusion criteria; 29% were persons who inject drugs and 13% were organ transplant recipients. Pseudomonas aeruginosa was the causative species in 98% of cases. Patients who experienced 42 day cure were more likely to be initially managed with first-line β-lactam agents compared with those who experienced clinical failure (97% versus 62%, P = 0.004). Treatment with first-line β-lactams was associated with shorter time to treatment initiation and a lower likelihood of infection due to MDR Pseudomonas spp. In the univariate model, patients who experienced 90 day mortality were more likely to have prosthetic valve endocarditis (57% versus 24%, P = 0.02), an intracardiac complication (36% versus 9%, P = 0.04) and a higher median (IQR) Pitt bacteraemia score [2.5 (2-3.8) versus 1 (0-2), P = 0.048]. Combination therapy did not improve clinical outcomes but did increase the rate of adverse effects resulting in drug discontinuation compared with monotherapy, (21% versus 0%, P = 0.08). This is the largest study of Pseudomonas endocarditis to date. We identified improved clinical outcomes when cefepime, piperacillin/tazobactam, ceftazidime or ceftolozane/tazobactam were used for initial treatment. We did not identify a clinical benefit for combination treatment.